Diffuse optical tomography (DOT) is an emerging imaging methodology for mapping human brain function. In contrast to positron emission tomography (PET) and magnetic resonance imaging (MRI), which use large scanners and require the subject to remain immobile inside a tube, DOT employs a wearable imaging cap. The DOT cap is well-suited for several situations not amenable to fixed scanner environments including imaging moving subjects who might otherwise require sedation, immovable subjects, such as patients in intensive care, and subjects with metal implants. The cap also has great potential for studies of human development in children that would benefit from enriched environments for a wider range of behavioral paradigms. DOT approaches have a number of potential benefits over previous optical approaches, including volumetric localization, quantitative imaging, and better discrimination of cortical signals from scalp and skull. The results of imaging human breast and small animals with DOT suggest a resolution of <1 cm resolution is possible on the peripheral cortex in adult humans, better still in infants and young children. However extension of DOT methods to application in mapping human brain function is difficult In this grant, we will address instrumentation challenges related to high-density, full-coverage imaging arrays and develop a new functional DOT system (DOT) for human brain activity (Aim 1). Complementary algorithms will be developed for reporting functional brain maps in a common coordinate system and for improving the contrast to background of stimulated brain signals (Aim 2). Feasibility will be established with comparative fMRI/DOT studies of human adults and children during rest and during visual, motor, auditory, and language tasks (Aim 3). Successful development of these new DOT methods will significantly enhance the image quality and reliability of DOT functional maps and increase the utility and impact of DOT for a wider variety of neuroscience applications. If the methods and experimental tasks developed in this proposal are successful, they will drive a larger program to include developmental studies such as literacy-related skills in younger, pre-literate children as well as in children with atypical development of such skills. [unreadable] [unreadable] [unreadable]